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V Suresh - One of the best experts on this subject based on the ideXlab platform.

  • local global galois theory of Arithmetic Function fields
    Israel Journal of Mathematics, 2019
    Co-Authors: David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the relationship between the local and global Galois theory of Function fields over a complete discretely valued field. We give necessary and sufficient conditions for local separable extensions to descend to global extensions, and for the local absolute Galois group to inject into the global absolute Galois group. As an application we obtain a local-global principle for the index of a variety over such a Function field. In this context we also study algebraic versions of van Kampen′s theorem, describing the global absolute Galois group as a direct limit of local absolute Galois groups.

  • local global galois theory of Arithmetic Function fields
    arXiv: Rings and Algebras, 2017
    Co-Authors: David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the relationship between the local and global Galois theory of Function fields over a complete discretely valued field. We give necessary and sufficient conditions for local separable extensions to descend to global extensions, and for the local absolute Galois group to inject into the global absolute Galois group. As an application we obtain a local-global principle for the index of a variety over such a Function field. In this context we also study algebraic versions of van Kampen's theorem, describing the global absolute Galois group as a pushout of local absolute Galois groups.

  • local global principles for zero cycles on homogeneous spaces over Arithmetic Function fields
    arXiv: Algebraic Geometry, 2017
    Co-Authors: Jeanlouis Colliotthelene, David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the existence of zero-cycles of degree one on varieties that are defined over a Function field of a curve over a complete discretely valued field. In particular, we show that local-global principles hold for such zero-cycles provided that local-global principles hold for the existence of rational points over extensions of the Function field. This assertion is analogous to a known result concerning varieties over number fields. We also show that our results hold more generally in the henselian case.

David Harbater - One of the best experts on this subject based on the ideXlab platform.

  • local global galois theory of Arithmetic Function fields
    Israel Journal of Mathematics, 2019
    Co-Authors: David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the relationship between the local and global Galois theory of Function fields over a complete discretely valued field. We give necessary and sufficient conditions for local separable extensions to descend to global extensions, and for the local absolute Galois group to inject into the global absolute Galois group. As an application we obtain a local-global principle for the index of a variety over such a Function field. In this context we also study algebraic versions of van Kampen′s theorem, describing the global absolute Galois group as a direct limit of local absolute Galois groups.

  • local global galois theory of Arithmetic Function fields
    arXiv: Rings and Algebras, 2017
    Co-Authors: David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the relationship between the local and global Galois theory of Function fields over a complete discretely valued field. We give necessary and sufficient conditions for local separable extensions to descend to global extensions, and for the local absolute Galois group to inject into the global absolute Galois group. As an application we obtain a local-global principle for the index of a variety over such a Function field. In this context we also study algebraic versions of van Kampen's theorem, describing the global absolute Galois group as a pushout of local absolute Galois groups.

  • local global principles for zero cycles on homogeneous spaces over Arithmetic Function fields
    arXiv: Algebraic Geometry, 2017
    Co-Authors: Jeanlouis Colliotthelene, David Harbater, Julia Hartmann, Daniel Krashen, Raman Parimala, V Suresh
    Abstract:

    We study the existence of zero-cycles of degree one on varieties that are defined over a Function field of a curve over a complete discretely valued field. In particular, we show that local-global principles hold for such zero-cycles provided that local-global principles hold for the existence of rational points over extensions of the Function field. This assertion is analogous to a known result concerning varieties over number fields. We also show that our results hold more generally in the henselian case.

Liu Zhe - One of the best experts on this subject based on the ideXlab platform.

  • A Family of Lightweight Twisted Edwards Curves for the Internet of Things
    Springer International Publishing, 2019
    Co-Authors: Ghatpande Sankalp, Großschädl Johann, Liu Zhe
    Abstract:

    Part 6: Internet of ThingsInternational audienceWe introduce a set of four twisted Edwards curves that satisfy common security requirements and allow for fast implementations of scalar multiplication on 8, 16, and 32-bit processors. Our curves are defined by an equation of the form $$-x^2 + y^2 = 1 + dx^2y^2$$ over a prime field $$\mathbb {F}_p$$, where d is a small non-square modulo p. The underlying prime fields are based on “pseudo-Mersenne” primes given by $$p = 2^k - c$$ and have in common that $$p \equiv 5 \bmod {8}$$, k is a multiple of 32 minus 1, and c is at most eight bits long. Due to these common features, our primes facilitate a parameterized implementation of the low-level Arithmetic so that one and the same Arithmetic Function is able to process operands of different length. Each of the twisted Edwards curves we introduce in this paper is birationally equivalent to a Montgomery curve of the form $$-(A+2)y^2 = x^3 + Ax^2 + x$$ where $$4/(A+2)$$ is small. Even though this contrasts with the usual practice of choosing A such that $$(A + 2)/4$$ is small, we show that the Montgomery form of our curves allows for an equally efficient implementation of point doubling as Curve25519. The four curves we put forward roughly match the common security levels of 80, 96, 112 and 128 bits. In addition, their Weierstraß representations are isomorphic to curves of the form $$y^2 = x^3 - 3x + b$$ so as to facilitate inter-operability with TinyECC and other legacy software

Zhe Liu - One of the best experts on this subject based on the ideXlab platform.

  • A Family of Lightweight Twisted Edwards Curves for the Internet of Things
    2018
    Co-Authors: Sankalp Ghatpande, Johann Großschädl, Zhe Liu
    Abstract:

    We introduce a set of four twisted Edwards curves that satisfy common security requirements and allow for fast implementations of scalar multiplication on 8, 16, and 32-bit processors. Our curves are defined by an equation of the form $$-x^2 + y^2 = 1 + dx^2y^2$$ over a prime field $$\mathbb {F}_p$$, where d is a small non-square modulo p. The underlying prime fields are based on “pseudo-Mersenne” primes given by $$p = 2^k - c$$ and have in common that $$p \equiv 5 \bmod {8}$$, k is a multiple of 32 minus 1, and c is at most eight bits long. Due to these common features, our primes facilitate a parameterized implementation of the low-level Arithmetic so that one and the same Arithmetic Function is able to process operands of different length. Each of the twisted Edwards curves we introduce in this paper is birationally equivalent to a Montgomery curve of the form $$-(A+2)y^2 = x^3 + Ax^2 + x$$ where $$4/(A+2)$$ is small. Even though this contrasts with the usual practice of choosing A such that $$(A + 2)/4$$ is small, we show that the Montgomery form of our curves allows for an equally efficient implementation of point doubling as Curve25519. The four curves we put forward roughly match the common security levels of 80, 96, 112 and 128 bits. In addition, their Weierstraß representations are isomorphic to curves of the form $$y^2 = x^3 - 3x + b$$ so as to facilitate inter-operability with TinyECC and other legacy software.

Victor Volfson - One of the best experts on this subject based on the ideXlab platform.